How To Build Wind Generator using Floppy Drive Stepper Motor

Floppy drive wind generator is a quite simple DIY project. Although construction looks like a toy, it can be used in various situations. On camping, fishing, sailing or wherever power greed is not available. Small wind generator can power or recharge AA/AAA batteries (Ni-Cd, Ni-Mh), mobile phones, MP3 players. You can connect light bulbs, LED light or similar devices that draw up to a few watts. The “heart” of home built wind generator is made out of parts scraped from an old 5.25″ floppy drive!

There was a good reason to use stepper motor salvaged from a floppy drive. PC technology is “aging” very quickly and floppy drive can nowadays be bought for a very low price. In most cases free of charge. Stepper motors are very convenient for small wind generators. First, because they do not need any kind of gearing mechanism and the rotor can be attached directly to a turbine – propeller. This can simplify construction work and also lowers the noise produced by the windmill. Step motor produces stable voltage even on low rpm (200 rpm) which is a great advantage comparing to DC alternators / motors. DC motors require at least 10 to 15 times higher rpm in order to achieve similar power output. This is very important, especially during the low wind speed periods.

Stable power supply is ensured using small electronic circuit (few diodes, resistor, condenser and integrated circuit). Anyone with previous soldering experience will be able to construct it.

When it is windy outside, generator of our small windmill produces electric energy sufficient for one (LED flashlight) or to charge a battery pack. Practical usage is virtually limitless, we have attached USB female connector (with stabilized voltage 5V) to our mini wind generator so that all modern mobile devices (iPod, iPad, cell phone, etc…) can now be powered by the wind…

5.25″ FLOPPY DRIVE WIND GENERATOR – CONSTRUCTION DETAILS

First, find an old generation PC286, open it and remove 5.25 inch floppy drive unit – Picture 1. As you already guessed, floppy drive will serve as a “donor” for the most important part – power generator stepper motor. After opening floppy drive unit, carefully extract stepper motor (pictures 2 and 3).

Drill two holes with stationary drill on the shaft as shown in Figure 4. This we allow you to directly attach the turbine (propeller) onto stepper rotor, using two screws.

Next, we will construct electronic power stabilizer (Picture 5). This circuit will rectify alternate current (convert it from AC to DC) generated by windmill and stabilize the voltage precisely at 5 volts (Picture 6) so that we can safely connect any USB device. Although we have used the printed circuit board, you can solder and interconnect all electronic components directly. You will need soldering iron and some tin with solder paste.

Picture 7 – Wind generator schematic diagram

Electronic components should be soldered according to the electric diagram above. Wires coming out of stepper motor should be connected to rectifiers, in our case diodes 1N4004 (picture 7 – shown on the left side).

WARNING! Stepper motor usually have 5 wires coming out although you can find those who have 4, 6 or 8 wires. It is important to determine which type of stepper motor you have in order to correctly connect the stepper with electronics of wind generator. Here you can find necessary details how to connect different stepper motors. It`s very hard to “burn” a stepper but caution is advised anyway!!!

We have bought USB extension cable (Picture 8) on e-bay, cut it in half and connected wires coming out of female USB connector directly to the output of windmill electronics (picture 7 – shown on the right side). USB extension cable has 4 wires, but we only need the outer two, plus and minus 5V (Picture 9).

If you want to use wind generator for battery charging only, you can build a lot simpler electronics than the one we have used (Picture 10).

WARNING! Before connecting any USB device it is MANDATORY to check polarity and exact voltage (it has to be between 4.9 and 5.3 Volts) on USB connector using multimeter!!!

Now we need to make the remaining mechanical parts for the wind generator. We need to prepare a bracket and a turbine (propeller). Bracket can be made out of aluminum tube with 3-4mm diameter. Do not forget to fix it firmly. If you plan to frequently move wind generator from one place to another, easiest solution would be to fix the bracket using an umbrella stand to ensure mobility and stability at the same time (Picture 11).

Generator (stepper motor) can be easily fastened directly to the bracket using clamps or using a metal “L” profile. Solution actually depends on whether you will use horizontal or vertical turbine. We made both versions, it is up to you to decide which you prefer.

If you pick horizontal axis wind turbine, you can create a three-bladed propeller using the meter, pen and scissors for cutting sheet metal. You will need a sheet metal panel 0.8×0.8m, 0.5mm thick. Cut out the pieces and form them as directed on the picture 12, and attach the turbine to the rotor of stepper motor with screws. In case you do not have time to make everything by yourself, you can buy finished propeller very cheap (Picture 14) in any well equipped hardware store. For vertical axis wind turbine, the simplest way is to make a turbine out of plastic bucket (paint container). Cut it in the middle, fix it onto round wooden / plastic plate (Picture 13). Finally, the whole windmill structure should be fixed on the generator rotor (stepper motor) with screws.

During strong winds (over 10 m/s), mini windmill can produce 5 watts of electricity on average. This is a maximum you can achieve with floppy drive stepper motor, but output power also depends on the dimensions of the propeller blades.

Vertical axis wind turbine is most suitable for roof mounting because it is far more efficient in turbulent wind conditions (fast and often changing wind direction). For outdoor usage – you can use windmill version with the horizontal axis and three-bladed turbine.

We are currently preparing new DIY project “100 watt Wind Turbine” which is entirely based on the mini windmill. 100 watts is enough power to supply a television set or a laptop. As a generator core we will use a stepper again, but this time from an old A3 dot-matrix printer.

Although the power of this wind generator is quite small, it can easily power LED lighting in your backyard (10-20 Hi-Power LED) or serve as autonomous power supply for mobile phone charging on camping. The most important thing is that successful construction of such mini wind generator encourages you to subsequently make a much stronger wind generator which can reduce consumption of non-renewable energy and decrease carbon footprint.